The regulation of cellular processes is mediated by dynamic byt specific interactions of regulatory elements with the nucleosomal and higher order structures of eukaryotic genomes. Through a variety of unknown mechanisms these interactions induce conformational changes in individual nucleosomes and their domain superstructures to control gene expression. The specific aims of this proposal are (1) to investigate and characterize the site-specificity of the DNA-protein interactions involved in the structural and functional organization of mammalian nuclei and (2) to correlate changes in the specificity of these interactions with alterations in the physiological parameters of cells, such as cell cycle position, growth rates and the effects of viral infections and transformations. The repetitive alphoid sequence families, which appear to be structural components of primate genomes, and their associated nuclear proteins will be examined. The Africian green monkey (AGM) component Alpha DNA and its chromatin will be the initial prototypical experimental system; the protein associations of other primate alphoid DNAs will also be analyzed. Recent findings in several systems suggest that some repeated sequences may be involved in gene regulation through effects on the spatial districtuion and rearrangements of genes. Other repeated sequences are located in the centromeric heterochromatin of metaphase chromosmes which are frequently involved in the structural rearrangement of chromosomes in evolution and in malignancy and human genetic diseases. Thus, the proposed study is relevant to uonderstanding not only the chromatin structure of repeated sequences, but also to gene expression and chromosome abnormalities. The methodologies include (a) selective nuclear extractions to prepare component Alpha DNP complexed containing only their tenaciously bound proteins, (b) chromatographic and electrophoretic fractionation of the alpha DNP complexes, (c) characterization of the bound proteins and their binding specifications by the "footprinting" modification of the DNA sequencing procedure, (d) an immunological study of the relatedness of alphoid DNP complexes isolated from different rimates and (e) an immunofluorescence microscopy mapping of the subnuclear locations of the alpha DNP complexes and their stability at these locations during cell cycle traverse and perturbations of cellular growth.